1. Field of the Invention
This invention relates to a mineral benefication device and process and is more particularly concerned with a method and apparatus for Ordinary and Submarine Mineral Beneficiation for the separation and concentration of particulate material from a fluid slurry.
2. Description of the Prior Art
Heretofore, particulate materials of diverse specific gravities carried in a fluidic medium were generally separated and concentrated through the use of sloping particle separators such as those dating back to the ancient riffle sluices to the more recent undercut sluice types including the spiral, the cone, the Lamflo concentrator and the undercut sluice tray. Such devices, which are exemplified by those disclosed in U.S. Pat. Nos. 1,291,137, 1,986,179 and 2,989,184, were so constructed as to be open to ambient atmospheric pressure. When these devices were used in placer mining and beneficiation of milled ores their operational efficiencies were limited, particularly in the separation and concentration of particulates of fine size, by the presence of surface turbulence and the necessity of maintaining a single flow rate through the entire separation circuit during processing. In these prior art devices this single flow rate had to be maintained at a velocity sufficient to transport all the particulate material being processed through the entire process circuit and therefore at such a flow velocity that there was a tendency to retain the very finest particles, in suspension. Also, in these devices the fluid carrier transport flow rate was inseparable from the particulates flow rate.
Particulates flow rate determines exposure time of the particulates at the point of selective separation when passing through the process circuit, and these prior art devices had no means to adjust particulates flow rate, i.e., exposure time, independently from the fluid carrier flow rate.
Indeed, these prior art devices had no means to readily adjust the proportional division and discharge from the uppermost strata and from the lowermost strata of the particulates being processed. These devices operated with a substantially fixed enrichment ratio usually necessitating successive processing stages to achieve an acceptable concentration of the relatively heavier mineral from an ore feed. As a part of their operation, a middlings product was usually generated by these devices, the product requiring recycling and additional material handling. Also, with these prior art devices, the feed density, i.e. the ratio of particulates to the fluid carrier, was a critical factor in the efficiency of the separating process and had to be maintained within close tolerances. For example, with some of these devices the feed density was recommended to be maintained within 5% limits. Furthermore, these prior art devices had no adjustable means to readily respond to a feedback signal to optimize process performance, nor were the general flow paths of the fluidic medium and the particulates separable.
To eliminate some of these undersirable features, a closed-chamber type separator was recently developed as disclosed in U.S. Pat. No. 3,537,581. Upon entering such a chamber through an inlet passage the flow rate of material was reduced and dissipated in a substantially larger space thereby creating a controllable factor capable of dictating the fallout pattern of the solid particulate material carried by the fluidic medium. Within the chamber, a partial separation of the fluid flow path and the solid flow path was achieved. The solid material, having fallen from a suspension in the fluidic medium as a result of the reduced flow rate, followed a gravity-directed path through a processing area that was operated under relatively smooth, laminar flow conditions, substantially void of surface turbulence.
Though the just described closed-chamber type separators have produced a decisive advance in the art of separating particulate materials, they have been lacking in certain respects.
For example, these devices have typically required intermittent suspensions of operations in order to recover the separated material. Input and discharge of particulates has not been automatically controlled. Gas blockage has frequently limited performance. Near complete separation of particles from the fluidic medium has not been achieved. Particulates flow rate has not been controlled independently from fluid flow rate and the proportional division and discharge from the uppermost strata and from the lowermost strata of particulates, being processed, has not been controlled.
The prior art closed chamber type separators have had no provisions for continuous operation of the process in a manner that would exempt the process from a fixed enrichment ratio; nor do they have provisions for continuous operation of the process with the elimination of a middlings product.
Feed density, as a critical factor in the operating efficiency of the prior art closed chamber process, has not been eliminated to any substantial extent nor have such prior art devices provided adjustable means to readily respond to a feed back signal to optimize process performance.
No means were provided to accommodate centrifugal delivery of particulates into the closed chamber.
Accordingly, it is a general object of the present invention to provide improved apparatus and process for separating and concentrating particulate materials which will overcome the disadvantages described above.
More specifically, it is an object of the present invention to provide an apparatus of the closed-chamber type for separating and concentrating particulate materials with improved operational performance for both ordinary and submarine applications.
Another object of the present invention is to provide an apparatus of the type described which is capable of purging gases trapped within the closed chamber.
Another object of the present invention is to provide apparatuses of the type described with automatic control means for controlling the delivery of material into the closed chamber and also discharge of material from the chamber as dictated by conditions within the chamber.
Another object of the present invention is to provide an apparatus and process for separating particulate material, which is capable of operation under water and is thus suitable for use on an ocean bed.
Another object of the present invention is to provide an apparatus and process for separating particulate material in which the surface turbulence of the particulate flow is eliminated, thereby preventing further disintegration of the particles which are to be separated.
Another object of the present invention is to provide an apparatus and process for separating particulate material which will eliminate the necessity of maintaining a constant flow rate through the entire process.
Another object of the present invention is to provide an apparatus and process for separating particulate material which can operate in a plurality of stages, the material being fed from one stage to the next automatically.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein particles, which are carried by a slurry when separated from the fluid thereof, are directed along separate paths from that of the fluid.
Another object of the present invention is to provide an apparatus and process for separating particulate material in which the flow rate of the fluid and the flow rate of the particles separated from the fluid can be individually adjusted and controlled, as desired.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein the time in which the particles are subjected to a separating force can be varied, as desired.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein the operation of the apparatus and process is automatically controlled.
Another object of the present invention is to provide an apparatus and process for separating particulate material in which the rate of input of the particles into the area of selective separation is controlled automatically by the rate of withdrawal of material from this area.
Another object of the present invention is to provide an apparatus and process for separating particulate material in which the discharge of the separated particles can be intermittent or continuous, as desired.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein a slurry containing the particulate material is subjected to a plurality of separating procedures and wherein the time in which the slurry is subjected to each operation can be varied, as desired.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein the material may be separated at an intermediate stage in the process, if desired.
Another object of the present invention is to provide an apparatus and process for separating particulate material in which the enrichment ratio of the resulting particulate material may be varied, as desired.
Another object of the present invention is to provide an apparatus and process with a means to readily adjust the proportional division and discharge from the uppermost strata and from the lower most strata of the particulates being processed.
Another object of the present invention is to provide an apparatus and process for separating particulate material in which a middling product is eliminated.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein the heavy constituents of a slurry may be effectively recovered, regardless of the feed density of the slurry.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein the maximum capacity of the apparatus and process can be readily and easily determined.
Another object of the present invention is to provide an apparatus and process for separating particulate material which, while utilizing a fluid, such as water, is incorporated into a closed system in which no appreciable additional water is required.
Another object of the present invention is to provide an apparatus and process for separating particulate material wherein the material may be readily and easily recycled, in the event more definite separation of the material is desired.
Other objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, wherein like characters of reference designate the corresponding parts throughout the several views.